This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Seminal fluid is the primary interactor with the female reproductive tract and has been shown to affect numerous physiological characteristics during mammalian reproduction;sperm motility and capacitation, female immunological suppression, and sperm competition. Characterizing the proteins involved in fertilization and reproduction is essential to understanding the evolutionary changes that have occurred within human and nonhuman primate lineages. In addition, the proteins involved in these processes have almost certainly been influenced by the evolution of diverse mating systems (polygamous versus monogamous) within primates. Gene loss and gain (duplication) may have played an important role in speciation and the evolution of mating systems. Despite this, only human seminal fluid has been extensively characterized on the proteomic level. Seminal fluid data from non-human primates is still lacking. To pursue these questions, I am using a proteomic approach to analyze seminal fluid from various primate species with diverse mating systems. Using mass spectrometry, I am identifying the protein contents in the seminal fluid ejaculates from the chimpanzee (Pan troglodytes) and Rhesus macaque (Macaca mulatta). Once the seminal fluid contents have been characterized within these primates, I will use a comparative proteomics and genomics approach to examine differences in protein content, relative and absolute protein abundance, and evolution across diverse primate mating systems.